Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$97.64	12.585%	$109.928	$109.93	$109.95	$109.90
Purchase #2	$196.94	13.436%	$223.4009	$223.40	$223.40	$223.40
Purchase #3	$49.40	12.149%	$55.4016	$55.40	$55.40	$55.40
Purchase #4	$227.68	11.226%	$253.2394	$253.24	$253.25	$253.20
Purchase #5	$250.79	9.152%	$273.7423	$273.74	$273.75	$273.70
Purchase #6	$124.71	7.541%	$134.1144	$134.11	$134.10	$134.10
Purchase #7	$32.40	9.276%	$35.4054	$35.41	$35.40	$35.40
7 purchase totals =	$979.56		$1,085.2320	$1,085.23	$1,085.25	$1,085.10